1. Field of the Invention
The present invention relates to a technique for measuring color in a measurement image for maintaining color stability in an image forming apparatus.
2. Description of the Related Art
In order to maintain color stability in an image forming apparatus, it is necessary to scan a measurement image (test pattern) and adjust various image processing conditions, image forming conditions, and the like. The test pattern is scanned by a color separation type color sensor, and the appropriate exposure time differs for each color. Japanese Patent Laid-Open No. 2007-274438 (Patent Document 1) proposes a technique in which the accumulation time of light receiving elements in a color sensor is changed according to the color and density of the formed image pattern. Accordingly, it is possible to detect the color and density of the image pattern with sufficient accuracy for any color and density of an image pattern.
However, since the appropriate accumulation time is determined by scanning a region that comprises the front half of one image pattern and the remaining region comprising the latter half of the image pattern is measured using the determined accumulation time, the size of the image pattern must be increased sufficiently. If the size per image pattern increases, the number of sheets needed will also increase. For example, this is because there are tens to hundreds of image patterns for creating a color matching profile such as an ICC profile. ICC is an abbreviation for International Color Consortium.